An investigation of the interaction of carbonyl compounds with the snowpack

Measurements of formaldehyde, acetaldehyde, and acetone in ambient and snow pack air were conducted as a part of the SNOW99 study in northern Michigan. Vertical profiles of ambient and snowpack air illustrate large concentrati on gradients through the top similar to 10 cm of the snowpack, implying a p ositive flux of these species from the surface. Snow chamber experiments th at involved flushing a snow-filled 34L Teflon-lined chamber with zero air a t 20 slpm indicated that release from the snow followed first order kinetic s, with decay constants of 0.19, 0.44, and 0.34 hr(-1) for formaldehyde, ac etaldehyde, and acetone, respectively. Although it is likely that temperatu re dependent adsorption/desorption processes play a role, the data are not inconsistent with loss from the snowpack via snow grain metamorphism. The d ata also imply that formaldehyde is not hydrated in the snow grain surface layer.